Ultrasonic transducer element chip, probe, electronic instrument, and ultrasonic diagnostic device

ABSTRACT

An ultrasonic transducer element chip includes a substrate defining an opening, an ultrasonic transducer element disposed at a position corresponding to the opening in a thickness direction of the substrate, and a reinforcing member connected to the substrate to cover the opening. The reinforcing member defines a ventilation passage from the opening to an outside of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/733,014 filed on Jun. 8, 2015, which is acontinuation application of U.S. patent application Ser. No. 13/804,872filed on Mar. 14, 2013, now U.S. Pat. No. 9,079,220. This applicationclaims priority to Japanese Patent Application No. 2012-078672 filed onMar. 30, 2012. The entire disclosures of U.S. patent application Ser.Nos. 14/733,014 and 13/804,872 and Japanese Patent Application No.2012-078672 are hereby incorporated herein by reference.

BACKGROUND

Technical Field

The present invention relates to an ultrasonic transducer element chip,a probe that uses the ultrasonic transducer element chip, and anelectronic instrument and an ultrasonic diagnostic device and the likethat use the probe.

Related Art

As described in Japanese Laid-Open Patent Publication No. 2011-82624,for example, an ultrasonic transducer element chip is provided with asubstrate. A plurality of openings are formed in the substrate. Anultrasonic transducer element is provided in each of the openings. Theultrasonic transducer element is provided with a vibrating film. Thevibrating film covers the openings from a surface of the substrate.

SUMMARY

When the openings are formed in the substrate, the strength of thesubstrate is deteriorated. The strength is insufficient with respect toforce in a thickness direction of the substrate. Therefore, when theultrasonic transducer element chip is pressed against a target to betested, the ultrasonic transducer element chip was sometimes damaged.

According to at least one embodiment of the present invention, anultrasonic transducer element chip that is thin and has sufficientstrength in resistance to pressing force in a thickness direction of asubstrate can be provided.

According to one aspect of the present invention, an ultrasonictransducer element chip includes a substrate defining an opening, anultrasonic transducer element disposed at a position corresponding tothe opening in a thickness direction of the substrate, and a reinforcingmember connected to the substrate to cover the opening. The reinforcingmember defines a ventilation passage from the opening to an outside ofthe substrate. Through the ventilation passage, an internal space of theopening and an external space of the substrate are in communication witheach other.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a perspective view schematically showing an example of anelectronic instrument, that is, an ultrasonic diagnostic deviceaccording to one embodiment of the present invention.

FIG. 2 is an enlarged front view of an ultrasonic probe.

FIG. 3 is an enlarged plan view of an ultrasonic transducer elementchip.

FIG. 4 is a sectional view along line 4-4 of FIG. 3.

FIG. 5 is a plan view of a reinforcing plate showing grooves.

FIG. 6 is an enlarged partial plan view of FIG. 5.

FIG. 7 is a block diagram schematically showing a circuit configurationof the ultrasonic diagnostic device.

FIG. 8 is a partial enlarged vertical sectional view schematicallyshowing a flexible film and a lower electrode formed on a silicon wafer.

FIG. 9 is a partial enlarged vertical sectional view schematicallyshowing a piezoelectric film and an upper electrode formed on the lowerelectrode.

FIG. 10 is a partial enlarged vertical sectional view schematicallyshowing a conductive film that covers the silicon wafer.

FIG. 11 is a partial enlarged vertical sectional view schematicallyshowing an opening formed in the silicon wafer, and a reinforcing platewafer.

FIG. 12 is a vertical sectional view of an ultrasonic transducer elementchip of the second embodiment corresponding to FIG. 4.

FIG. 13 is an enlarged partial plan view of an ultrasonic transducerelement chip of the second embodiment corresponding to FIG. 6.

FIG. 14 is a partial enlarged vertical sectional view schematicallyshowing a groove formed on the reverse surface of a silicon wafer.

FIG. 15 is a vertical sectional view of an ultrasonic transducer elementchip of the third embodiment corresponding to FIG. 4.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Next, embodiments of the present invention will be explained withreference to the attached drawings. The embodiments explained belowshall not be construed as unreasonably limiting the subject matter ofthe present invention described in the claims, and all the elementsexplained in the embodiments are not necessarily essential to thesolving means of the present invention.

(1) Overall Configuration of Ultrasonic Diagnostic Device

FIG. 1 schematically shows a configuration of an ultrasonic diagnosticdevice 11 as an example of an electronic instrument according to anembodiment of the present invention. The ultrasonic diagnostic device 11is provided with a device terminal 12 and an ultrasonic probe (probe)13. The device terminal 12 and the ultrasonic probe 13 are connected toeach other through a cable 14. The device terminal 12 and the ultrasonicprobe 13 communicate an electric signal through the cable 14. A displaypanel (display device) 15 is incorporated in the device terminal 12. Ascreen of the display panel 15 is exposed on a surface of the deviceterminal 12. As described later, in the device terminal 12, an image isgenerated based on ultrasonic waves detected with the ultrasonic probe13. Imaged detection results are displayed on the screen of the displaypanel 15.

As shown in FIG. 2, the ultrasonic probe 13 has a case 16 (one exampleof a case member). An ultrasonic transducer element chip (hereinafterreferred to as “element chip”) 17 is accommodated in the case 16. Asurface of the element chip 17 may be exposed on a surface of the case16. The element chip 17 outputs ultrasonic waves from the surfacethereof, and receives reflected waves of ultrasonic waves. Also, theultrasonic probe 13 may be provided with a probe head 13 b removablycoupled with a probe main body 13 a. In such an instance, the elementchip 17 may be incorporated in the case member of the probe head 13 b,which is configured to be coupled to the probe main body 13 a.

(2) Configuration of Ultrasonic Transducer Element Chip of FirstEmbodiment

FIG. 3 schematically shows a plan view of the element chip 17 of thefirst embodiment. The element chip 17 is provided with a substrate 21.An element array 22 is formed on a surface (first surface) of thesubstrate 21. The element array 22 is constructed with an arrangement ofultrasonic transducer elements (hereinafter referred to as “elements”)23. The arrangement is formed in a matrix having a plurality of rows anda plurality of columns. Each element 23 has a piezoelectric elementsection. The piezoelectric element section is constructed of a lowerelectrode 24, an upper electrode 25, and a piezoelectric film 26. Thepiezoelectric film 26 is sandwiched between the lower electrode 24 andthe upper electrode 25 in each element 23.

The lower electrode 24 has a plurality of first conductive bodies 24 a.The first conductive bodies 24 a extend in a column direction of thearrangement in parallel to each other. One first conductive body 24 a isassigned to each column of the elements 23. One first conductive body 24a is provided in common with respect to the piezoelectric films 26 ofthe elements 23 aligned in the column direction of the arrangement. Bothends of the first conductive body 24 a are connected to a pair ofextraction wirings 27, respectively. The extraction wirings 27 extend ina row direction of the arrangement in parallel to each other. Therefore,all the first conductive bodies 24 a have the same length. In thismanner, the lower electrode 24 is provided in common with respect to theelements 23 of the entire matrix.

The upper electrode 25 has a plurality of second conductive bodies 25 a.The second conductive bodies 25 a extend in a row direction of thearrangement in parallel to each other. One second conductive body 25 ais assigned to each row of the elements 23. One second conductive body25 a is provided in common with respect to the piezoelectric films 26 ofthe elements 23 aligned in the row direction of the arrangement. Powerdistribution to the elements 23 is switched for each row. Line scanningor sector scanning is achieved corresponding to such switching of powerdistribution. Since the elements 23 in one row output ultrasonic wavesat the same time, the number of the elements 23 in one row, that is, thenumber of columns of the arrangement can be determined based on theoutput level of ultrasonic waves. For example, the number of columns maybe set to be around 10-15. In the drawing, five columns are illustratedfor simplicity. The number of row s of the arrangement can be determinedbased on the extent of an area to be scanned. For example, the number ofrow s may be set to be 128 or 256. In the drawing, eight rows areillustrated for simplicity. Also, regarding the arrangement, a zigzagpattern may be used. In the zigzag pattern, a group of the elements 23in an even row may be displaced with respect to a group of the elements23 in an odd row by one-half of the column pitch. The number of theelements in one of an odd row and an even row may be smaller than thenumber of the elements in the other of an odd row and an even row byone. Furthermore, the role of the lower electrode 24 and the role of theupper electrode 25 may be switched. Specifically, the upper electrodemay be connected in common to the elements 23 of the entire matrix, andthe lower electrode may be connected in common to the elements 23 ineach row of the arrangement.

The outer edge of the substrate 21 has a first side 21 a and a secondside 21 b that are opposed and partitioned by a pair of straight lines29 parallel to each other. In the peripheral region 31 that extendsbetween the outline of the element array 22 and the outer edge of thesubstrate 21, a first terminal array 32 a of one line is arrangedbetween the first side 21 a and the outline of the element array 22, anda second terminal array 32 b of one line is arranged between the secondside 21 b and the outline of the element array 22. One line of the firstterminal array 32 a can be formed parallel to the first side 21 a. Oneline of the second terminal array 32 b can be formed parallel to thesecond side 21 b. The first terminal array 32 a is constructed of a pairof lower electrode terminals 33 and a plurality of upper electrodeterminals 34. Similarly, the second terminal array 32 b is constructedof a pair of lower electrode terminals 35 and a plurality of upperelectrode terminals 36. The lower electrode terminals 33 and 35 areconnected to both ends of each of the extraction wiring 27,respectively. It is sufficient for the extraction wirings 27 and thelower electrode terminals 33 and 35 to be formed plane-symmetricallywith respect to a vertical plane that bisects the element array 22. Theupper electrode terminals 34 and 36 are connected to both ends of eachof the second conductive bodies 25 a, respectively. It is sufficient forthe second conductive bodies 25 a, the upper electrode terminals 34 and36 to be formed plane-symmetrically with respect to the vertical planethat bisects the element array 22. Here, the outline of the substrate 21is formed in a rectangle. The outline of the substrate 21 may also besquare or trapezoidal.

A first flexible printed substrate 37 is coupled with the substrate 21.The first flexible printed substrate 37 covers the first terminal array32 a. Conductive lines, that is, first signal lines 38 are formed at oneend of the first flexible printed substrate 37 corresponding to thelower electrode terminals 33 and the upper electrode terminals 34,respectively. The first signal lines 38 are respectively opposed to thelower electrode terminals 33 and the upper electrode terminals 34, andrespectively bonded thereto. Similarly, a second flexible printedsubstrate 41 covers the substrate 21. The second flexible printedsubstrate 41 covers the second terminal array 32 b.

Conductive lines, that is, second signal lines 42 are formed at a firstend 41 a of the second flexible printed substrate 41 corresponding tothe lower electrode terminals 35 and the upper electrode terminals 36,respectively. The second signal lines 42 are respectively opposed to thelower electrode terminals 35 and the upper electrode terminals 36, andrespectively bonded thereto.

As shown in FIG. 4, each of the elements 23 has a vibrating film 43.When constructing the vibrating film 43, an opening 45 is formed in eachof the elements 23 on a substrate base 44 of the substrate 21. Theopenings 45 are arranged in an array pattern with respect to thesubstrate base 44. A flexible film 46 is formed on the entire surface(first surface) of the substrate base 44. The flexible film 46 isconstructed of a silicon oxide (SiO₂) layer 47 layered on the surface ofthe substrate base 44, and a zirconium oxide (ZrO₂) layer 48 layered ona surface of the silicon oxide layer 47. The flexible film 46 contactsthe openings 45. In this manner, a part of the flexible film 46 servesas the vibrating film 43 corresponding to the outline of the opening 45.The film thickness of the silicon oxide layer 47 can be determined basedon the resonance frequency.

The lower electrode 24, the piezoelectric film 26, and the upperelectrode 25 are layered on a surface of the vibrating film 43 in thisorder. For the lower electrode 24, a layered film of titanium (Ti),iridium (Ir), platinum (Pt), and titanium (Ti) can be used, for example.The piezoelectric film 26 may be formed of piezoelectric zirconatetitanate (PZT), for example. The upper electrode 25 may be formed ofiridium (Ir), for example. Another conductive material may be used forthe lower electrode 24 and the upper electrode 25, and anotherpiezoelectric material may be used for the piezoelectric film 26. Here,the piezoelectric film 26 completely covers the lower electrode 24 underthe upper electrode 25. The function of the piezoelectric film 26prevents short circuits between the upper electrode 25 and the lowerelectrode 24.

A protective film 49 is layered on the surface of the substrate 21. Theprotective film 49 covers, for example, the entire surface of thesubstrate 21. As a result, the protective film 49 covers the elementarray 22, the first terminal array 32 a, the second terminal array 32 b,a first end 37 a of the first flexible printed substrate 37, and thefirst end 41 a of the second flexible printed substrate 41. For example,a silicone resin film may be used for the protective film 49. Theprotective film 49 protects the configuration of the element array 22,the bonding of the first terminal array 32 a and the first flexibleprinted substrate 37, and the bonding of the second terminal array 32 band the second flexible printed substrate 41.

Partition walls 51 are laid out between the adjacent openings 45. Theopenings 45 are partitioned by the partition walls 51. The wallthickness “t” of the partition wall 51 corresponds to the intervalbetween the hollow spaces of the openings 45. The partition wall 51defines two wall surfaces in planes extending in parallel to each other.The wall thickness “t” of the partition wall 51 corresponds to theinterval between the wall surfaces. Specifically, the wall thickness “t”can be defined by the length of a vertical line that is orthogonal tothe wall surfaces and sandwiched between the wall surfaces. The wallheight “H” of the partition wall 51 corresponds to the depth of theopening 45. The depth of the opening 45 corresponds to the thickness ofthe substrate base 44. Therefore, the wall height “H” of the partitionwall 51 can be defined as the length of the wall surface defined in thethickness direction of the substrate base 44. Since the substrate base44 has a uniform thickness, the partition wall 51 can have a uniformwall height “H” over the entire length. When the wall thickness “t” ofthe partition wall 51 is decreased, the arrangement density of thevibrating film 43 can be increased. This can contribute to downsizing ofthe element chip 17. When the wall height “H” of the partition wall 51is larger than the wall thickness “t”, the bending rigidity of theelement chip 17 can be increased. Consequently, the interval between theopenings 45 is set to be smaller than the depth of the opening 45.

A reinforcing plate (reinforcing member) 52 is fixed to a reversesurface (second surface) of the substrate base 44 on the opposite sideof the surface of the substrate base 44. The reverse surface of thesubstrate base 44 is overlaid on a surface of the reinforcing plate 52.The reinforcing plate 52 covers the openings 45 with the reverse surfaceof the element chip 17. The reinforcing plate 52 may have a rigid basematerial. For example, the reinforcing plate 52 may be formed of asilicon substrate. The plate thickness of the substrate base 44 is setto be around 100 μm, and the plate thickness of the reinforcing plate 52is set to be around 100-150 μm. Here, the partition walls 51 are bondedto the reinforcing plate 52. The reinforcing plate 52 is bonded to eachof the partition walls 51 in at least one bonding region. An adhesivecan be used for bonding. In addition to superimposing of the substratebase 44 and the reinforcing member 52, “overlaid” also includeslamination of a reinforcing material on the reverse surface of thesubstrate base 44, and connection of the substrate base 44 and thereinforcing plate 52 arranged opposite each other.

A plurality of linear grooves (groove parts) 53 are formed on thesurface of the reinforcing plate 52. The grooves 53 divide the surfaceof the reinforcing plate 52 into a plurality of planes 54. The pluralityof planes 54 expand within one hypothetical plane HP. The reversesurface of the substrate base 44 expands within that hypothetical planeHP. The partition wall 51 is bonded to the plane 54. The grooves 53 sinkfrom the hypothetical plane HP. The cross section shape of the groove 53can be a quadrangle, a triangle, a semi-circle or another shape.

As shown in FIG. 5, the openings 45 form a line in a first direction D1.The centroids 45 c of the outline shapes of the openings 45 are arrangedat an equal pitch on a straight line 56 in the first direction D1. Sincethe openings 45 are formed by copying a single outline shape, theopenings 45 of the same shape are arranged repeatedly at a uniformpitch. For example, an outline 45 a of the opening 45 is defined as aquadrangle. Specifically, it is formed in a rectangle. The long side ofthe rectangle is made to coincide with the first direction D1. Since theopening 45 has a rectangular outline 45 a in this way, the partitionwall 51 can have a uniform wall thickness “t” over the entire length. Insuch an instance, the bonding region of the partition walls 51 may be aregion that includes a center position of the long side. In particular,the bonding region of the partition walls 51 may be a region thatincludes the entire length of the long side. The partition walls 51 maybe surface-bonded to the reinforcing plate 52 with respect to the entiresurface between the openings 45 over the entire length of the long side.Also, the bonding region of the partition walls 51 may be located in atleast one position of each side of the quadrangle. The bonding region ofthe partition walls 51 may continuously surround the quadrangle. Thepartition walls 51 may be surface-bonded to the reinforcing plate 52with respect to the entire surface between the openings 45 over theentire periphery of the quadrangle.

The grooves 53 are aligned in the first direction D1 mutually parallelat a fixed interval. The grooves 53 extend in a second direction D2 thatintersects with the first direction D1. Both ends of the grooves 53 openat the end surfaces 57 a and 57 b of the reinforcing plate 52. In a planview seen from the direction orthogonal to the surface of the substrate21, specifically, the thickness direction of the substrate 21, onegroove 53 cuts across one line (here it is one column) of outlines 45 aof the openings 45 in sequence. Each of the openings 45 has at least onegroove 53 connected. Here, the second direction D2 is orthogonal to thefirst direction D1.

Therefore, the grooves 53 cut across the outlines 45 a of the openings45 in the short side direction of the rectangle.

As shown in FIG. 6, between the planes 54, the grooves 53 formventilation passages 58 a and 58 b between the substrate base 44 and thereinforcing plate 52. In this way, the space within the groove 53 ismade to communicate with the internal space of the opening 45. Theventilation passages 58 a and 58 b ensure mutual communication betweenthe internal spaces of the openings 45 and the external space of thesubstrate 21. In a plan view seen from the thickness direction of thesubstrate 21, one groove 53 cuts across one line (here it is one column)of the outlines 45 a of the openings 45 in sequence, so the openings 45are connected successively by the ventilation passage 58 a. Both ends ofthe groove 53 are open at the end surfaces 57 a and 57 b of thereinforcing plate 52. In this way, the ventilation passage 58 b opensfrom the opening 45 of the line end to outside the outer edge of thesubstrate 21.

(3) Circuit Configuration of Ultrasonic Diagnostic Device

As shown in FIG. 7, an integrated circuit has a multiplexer 61, and atransmitting and receiving circuit 62. The multiplexer 61 has a group ofports 61 a on the element chip 17 side, and a group of ports 61 b on thetransmitting and receiving circuit 62 side. The first signal lines 38and the second signal lines 42 are connected to the group of ports 61 avia first wirings 54. In this manner, the group of ports 61 a areconnected to the element array 22. A prescribed number of signal lines63 within the integrated circuit chip 55 are connected to the group ofports 61 b on the transmitting and receiving circuit 62 side. Theprescribed number corresponds to the number of rows of the elements 23output simultaneously when scanning. The multiplexer 61 controlsinterconnection between the ports on the cable 14 side and the ports onthe element chip 17 side.

The transmitting and receiving circuit 62 has a prescribed number ofchanging switches 64. The changing switches 64 are connected to thecorresponding signal lines 63, respectively. The transmitting andreceiving circuit 62 has a transmission channel 65 and a receptionchannel 66 for each of the changing switches 64. The transmissionchannel 65 and the reception channel 66 are connected to the changingswitch 64 in parallel. The changing switch 64 selectively connects thetransmission channel 65 and the reception channel 66 to the multiplexer61. A pulser 67 is incorporated in the transmission channel 65. Thepulser 67 outputs a pulse signal at a frequency corresponding to theresonance frequency of the vibrating film 43. An amplifier 68, alow-pass filter (LPF) 69, and an analog-digital converter (ADC) 71 areincorporated in the reception channel 66. A detection signal of each ofthe elements 23 is amplified, and converted into a digital signal.

The transmitting and receiving circuit 62 has a driving/receivingcircuit 72. The transmission channel 65 and the reception channel 66 areconnected to the driving/receiving circuit 72. The driving/receivingcircuit 72 controls the pulser 67 simultaneously depending on the stateof scanning. The driving/receiving circuit 72 receives a digital signalof a detection signal depending on the state of scanning. Thedriving/receiving circuit 72 is connected to the multiplexer 61 througha control line 73. The multiplexer 61 conducts control ofinterconnection based on a control signal supplied from thedriving/receiving circuit 72.

A processing circuit 74 is incorporated in the device terminal 12. Theprocessing circuit 74 can be provided with a central processing unit(CPU) 74 and a memory, for example. The entire operation of theultrasonic diagnostic device 11 is controlled in accordance withprocessing of the processing circuit 74. The processing circuit 74controls the driving/receiving circuit 72 in accordance withinstructions input by a user. The processing circuit 74 generates animage in accordance with a detection signal of the element 23. The imageis specified by drawing data.

A drawing circuit 75 is incorporated in the device terminal 12. Thedrawing circuit 75 is connected to the processing circuit 74. Thedisplay panel 15 is connected to the drawing circuit 75. The drawingcircuit 75 generates a driving signal in accordance with drawing datagenerated in the processing circuit 74. The driving signal is sent tothe display panel 15. As a result, an image is displayed on the displaypanel 15.

(4) Operation of Ultrasonic Diagnostic Device

Next, the operation of the ultrasonic diagnostic device 11 will beexplained briefly. The processing circuit 74 gives the driving/receivingcircuit 72 instructions to transmit and receive ultrasonic waves. Thedriving/receiving circuit 72 supplies a control signal to themultiplexer 61, and supplies a driving signal to each of the pulsers 67.The pulser 67 outputs a pulse signal in response to the supply of thedriving signal. The multiplexer 61 connects the port of the group ofports 61 a to the port of the group of ports 61 b in response to theinstructions of the control signal. The pulse signal is supplied to theelements 23 for each row through the lower electrode terminals 33, 35and the upper electrode terminals 34, 36 in response to the selection ofthe port. The vibrating film 43 vibrates in response to the supply ofthe pulse signal. As a result, desired ultrasonic waves are emittedtoward a target (for example, the inside of a human body).

After ultrasonic waves are transmitted, the changing switch 64 isswitched. The multiplexer 61 maintains the connection relation of theports. The changing switch 64 establishes a connection between thereception channel 66 and the signal line 63 instead of a connectionbetween the transmission channel 65 and the signal line 63. Reflectedwaves of ultrasonic waves vibrate the vibrating film 43. As a result, adetection signal is output from the element 23. The detection signal isconverted into a digital signal, and sent into the driving/receivingcircuit 72.

Transmission and reception of ultrasonic waves are repeated. Forrepeating transmission and reception of ultrasonic waves, themultiplexer 61 changes the connection relation of the ports. As aresult, line scanning or sector scanning is achieved. When scanning isfinished, the processing circuit 74 generates an image based on thedigital signal of the detection signal. The generated image is displayedon the screen of the display panel 15.

In the element chip 17, the element 23 can be formed to be thin. Theelement 23 can be formed on the thin substrate 21. Even in a case wherethe reinforcing plate 52 is fixed to the substrate 21, the element chip17 can be formed to be thin. At the same time, the reinforcing plate 52reinforces the strength of the substrate 21. In particular, since thewall thickness “t” is smaller than the wall height “H” in the partitionwall 51, sufficient rigidity of the partition wall 51 can be obtained inthe thickness direction of the substrate 21 due to the section modulus.Force in the thickness direction of the substrate 21 can be transmittedthrough the partition wall 51 and supported by the reinforcing plate 52.In this manner, the element chip 17 has sufficient strength in thethickness direction of the substrate 21. Also, even when the platethickness of the substrate 21 is set to be around 100 μm, for example,the reinforcing plate 52 can prevent the substrate 21 from beingdamaged. On the other hand, in a case where the element array isconstructed of a bulk-type ultrasonic transducer element, the platethickness of the substrate is set to be around several millimeters. Evenwhen the reinforcing plate 52 is bonded, for example, the thickness ofthe element chip 17 can be reduced securely compared to the case wherethe element array is constructed of a bulk-type ultrasonic transducerelement. In addition, since the acoustic impedance of the vibrating film43 is close to that of a human body compared to a bulk-type ultrasonictransducer element, an acoustic impedance matching layer can be omittedin the element chip 17 unlike in the case of a bulk-type ultrasonictransducer element. Omission of the matching layer can furthercontribute to making the element chip 17 thinner.

The reinforcing plate 52 is bonded to each of the partition walls 51 inat least one bonding region. When the partition walls 51 are bonded tothe reinforcing plate 52, the movement of the partition walls 51 isrestricted by the reinforcing plate 52. Thus, vibration of the partitionwalls 51 can be prevented. As a result, crosstalk between the elements23 can be prevented. Further, when the movement of the partition walls51 is restricted, vibration of the partition walls 51 can be preventedfrom acting on ultrasonic vibration of the elements 23. Then, ultrasonicvibration in a clear vibration mode can be obtained in the elements 23.When vibration of the partition walls 51 is avoided, the amplitude ofultrasonic vibration can be prevented from being decreased. On the otherhand, when the partition wall 51 moves, a distorted vibration modehaving a lower frequency than the vertical vibration mode of thevibrating film 43 occurs. Furthermore, the kinetic energy of thevibrating film 43 decreases by the movement amount of the partition wall51, and the amplitude of the vibration decreases.

At this time, though the spaces within the openings 45 are enclosed bythe flexible film 46 (vibrating film 43) and the reinforcing plate 52,the grooves 53 ensure ventilation between the internal space of eachopening 45 and the external space of the substrate 21. Therefore, theinternal spaces of the openings 45 are not sealed tightly. As a result,the internal spaces of the openings 45 are connected to the atmosphericspace. The internal space of the openings 45 can easily follow ambientpressure fluctuations. In this way, it is possible to reliably avoiddamage to the elements 23. If by chance the internal space of theopening 45 is sealed airtight, there will be concern for damage to theultrasonic transducer element due to pressure fluctuations. Here, theexternal space is the space separated from the internal space by thesubstrate 21, the flexible film 46, and the reinforcing plate 52,meaning that this is a significantly larger space than the internalspace.

The bonding region of the partition walls 51 can be a region thatincludes a center position of the long side. Therefore, a part of thepartition walls 51 in which the amplitude of vibration is large isbonded to the reinforcing plate 52. As a result, vibration of thepartition walls 51 can be effectively prevented. Also, the bondingregion of the partition walls 51 can be a region that includes theentire length of the long side. When the partition walls 51 are bondedto the reinforcing plate 52 over the entire length of the long side,vibration of the partition walls 51 can be securely prevented. Further,the partition walls 51 can be surface-bonded with respect to the entiresurface between the openings 45 over the entire length of the long side.When the partition walls 51 are surface-bonded to the reinforcing plate52 with respect to the entire surface between the openings 45 over theentire length of the long side, vibration of the partition walls 51 canbe securely prevented.

It is sufficient that the bonding region of the partition walls 51 belocated in at least one position of each side of the quadrangle. Whenthe partition walls 51 are bonded to the reinforcing plate 52 in eachside of the quadrangle, vibration of the partition walls 51 can besecurely prevented. Also, the bonding region of the partition walls 51can continuously surround the quadrangle. When the partition walls 51are bonded to the reinforcing plate 52 with respect to the entire regionof the quadrangle, vibration of the partition walls 51 can be securelyprevented. Further, the partition walls 51 can be surface-bonded withrespect to the entire surface between the openings 45 over the entireperiphery of the quadrangle. When the partition walls 51 aresurface-bonded to the reinforcing plate 52 with respect to the entiresurface between the openings 45 over the entire periphery of thequadrangle, vibration of the partition walls 51 can be securelyprevented.

(5) Method for Manufacturing Ultrasonic Transducer Element Chip of FirstEmbodiment

As shown in FIG. 8, the lower electrode 24, the extraction wiring 27,and the lower electrode terminals 33, 35 (not shown in the drawingssubsequent to FIG. 8) are formed on a surface of a silicon wafer(substrate) 78 for each element chip 17. Prior to forming the lowerelectrode 24, the extraction wiring 27, and the lower electrodeterminals 33, 35, a silicon oxide film 79 and a zirconium oxide film 81are formed on the surface of the silicon wafer 78 successively. Aconductive film is formed on a surface of the zirconium oxide film 81.The conductive film is constructed as a layered film of titanium,iridium, platinum, and titanium. The lower electrode 24, the extractionwiring 27, and the lower electrode terminals 33, 35 are formed from theconductive film by a photolithographic technique.

As shown in FIG. 9, the piezoelectric film 26 and the upper electrode 25are formed on a surface of the lower electrode 24 for each element 23.Prior to forming the piezoelectric film 26 and the upper electrode 25, apiezoelectric material film and a conductive film are formed on thesurface of the silicon wafer 78. The piezoelectric material film isconstructed of a PZT film. The conductive film is constructed of aniridium film. The piezoelectric film 26 and the upper electrode 25 areformed from the piezoelectric material film and the conductive film foreach element 23 by a photolithographic technique.

Next, as shown in FIG. 10, a conductive film 82 is formed on the surfaceof the silicon wafer 78. The conductive film 82 connects the upperelectrodes 25 with respect to each other for each row in each elementchip 17. Also, the upper electrode 25 and the upper electrode terminals34, 36 are formed from the conductive film 82 by a photolithographictechnique.

Next, as shown in FIG. 11, the openings 45 of an array pattern areformed from the reverse surface of the silicon wafer 78. For forming theopenings 45, an etching treatment is conducted. The silicon oxide film79 serves as an etching stop layer. The vibrating film 43 is dividedinto the silicon oxide film 79 and the zirconium oxide film 81. Afterthe openings 45 are formed, a surface of a reinforcing plate wafer 83 issuperimposed on the reverse surface of the silicon wafer 78. Forexample, a rigid insulating substrate can be used for the wafer 83. Asilicon wafer can be used for the insulating substrate. Before bonding,linear grooves 84 are formed on the surface of the reinforcing platewafer 83. The grooves 84 extend in parallel to each other at equalintervals. At least one end of the groove 84 is open at the end surfaceof the wafer 83. An adhesive can be used for bonding, for example. Afterbonding, each of the element chips 17 is cut out of the silicon wafer78. The grooves 84 provide the grooves 53.

When grooves 84 are formed in this way, even when the silicon wafer 78and the wafer 83 are superimposed in air or in another gas atmosphere,superimposing can be achieved relatively easily. On the other hand, whenthe reverse surface of the silicon wafer 78 is superimposed on an evenplane, the gas is pushed into each opening 45 interior by the plane ofthe reinforcing plate wafer. At atmospheric pressure, gas of greatervolume than the volume of the space within the opening 45 tries toremain inside the openings 45. When extra gas does not escape from theinterval between the silicon wafer 78 and the reinforcing plate wafer atthe same time as sealing off of the openings 45, it is not possible toachieve binding together of the silicon wafer 78 and the reinforcingplate wafer.

(6) Ultrasonic Transducer Element Chip of Second Embodiment

FIG. 12 schematically shows the ultrasonic transducer element chip 17 aof the second embodiment. With this element chip 17 a, a plurality ofgroove (groove parts) 86 are arranged on the reverse surface of thesubstrate 21. The grooves 86 divide the reverse surface of the substrate21 at the bottom edge of the partition wall 51 into a plurality ofplanes 87. The plurality of planes 87 expand within one hypotheticalplane HP. The surface of the reinforcing plate 52 expands within thathypothetical plane HP. The grooves 86 sink from the hypothetical planeHP. The cross section shape of the groove 86 can be a quadrangle, atriangle, a semi-circle or another shape. As shown in FIG. 13, thegrooves 86 between the planes 87 form the ventilation passages 88 a, 88b between the substrate base 44 and the reinforcing plate 52. In thisway, the spaces within the grooves 86 are connected to the spaces withinthe openings 45. The ventilation passages 88 a, 88 b mutually connectinside and outside the spaces within the openings 45. In this way,ventilation is ensured between the space within the openings 45 andoutside the openings 45. With one line (here it is one column) ofopenings 45, openings 45 are successively connected to each other by theventilation passage 88 a. The opening 45 of the line end and the outsideof the outer edge of the substrate 21 are connected by the ventilationpassage 88 b. In this way, the opening 45 of the line end is open to theoutside of the outer edge of the substrate 21. The remainder of theconstitution can be constituted in the same manner as the element chip17. In the drawing, equivalent constitutions and structures to those ofthe element chip 17 are given the same reference code numbers.

As shown in FIG. 14, with the method of manufacturing the element chip17 a, before forming the openings 45, the grooves 89 are formed on thereverse surface of the silicon wafer 78. For forming the grooves 89, forexample, a lithographic technique may be used. On the reverse surface ofthe silicon wafer 78, for example, a resist film 91 is formed. A patternof the grooves 89 is formed on the resist film 91. In this way, when thegrooves 89 are formed, the resist film 89 is removed. The same as inFIG. 10, an array of openings 45 is formed from the reverse surface ofthe silicon wafer 78. When each element chip 17 a is cut out from thesilicon wafer 78, the grooves 89 provide the grooves 86.

(7) Ultrasonic Transducer Element Chip of Third Embodiment

FIG. 15 schematically shows the ultrasonic transducer element chip 17 bof the third embodiment. With this element chip 17 b, at least a portionof one of the substrate 21 and the reinforcing plate 52 is constitutedusing a porous material. This kind of porous material is arranged atleast between the openings 45 and between the opening 45 of the line endand the outer edge of the substrate 21. Here, the reinforcing plate 52is formed from the porous material. The pores of the porous material aremutually and continuously lined so as to form the ventilation passages.The remainder of the constitution can be constituted in the same manneras the element chip 17. In the drawing, equivalent constitutions andstructures to those of the element chip 17 are given the same referencecode numbers.

While the present embodiment has been explained in detail as above, itwill be apparent to those skilled in the art that various modificationscan be made herein without substantially departing from the new mattersand the effect of the present invention. Therefore, all suchmodifications are included in the scope of the invention. For example,the terms used in the specification or the drawings at least oncetogether with a different term having a broader or similar meaning canbe replaced with the different term in any portion of the specificationor the drawings. Also, the configurations and operations of theultrasonic diagnostic device 11, the ultrasonic probe 13, the probe head13 b, the element chips 17, 17 a, and 17 b, the element 23 and the likeare not limited to the present embodiment, and various modifications arepossible.

In the ultrasonic transducer element chip according to the embodiment,the ultrasonic transducer elements can be formed to be thin. Theultrasonic transducer elements can be formed in a thin substrate. Evenin a case where the reinforcing member is fixed to a substrate, theultrasonic transducer element chip can be formed to be thin. Inaddition, since the reinforcing member is fixed on the second surface ofthe substrate, it is possible for the strength of the substrate to bereinforced in the substrate thickness direction. At this time, theinternal spaces of the openings are in communication with the externalspace of the substrate. Ventilation is ensured between the internalspaces of the openings and the external space of the substrate.Therefore, the internal spaces of the openings are not sealed tight. Theinternal spaces of the openings can easily follow ambient pressurefluctuations. In this way, it is possible to reliably avoid damage tothe ultrasonic transducer element. If by chance the internal spaces ofthe openings are sealed airtight, there will be concern for damage tothe ultrasonic transducer element due to pressure fluctuations.

The reinforcing member may be bonded to a partition wall section of thesubstrate between the openings in at least one bonding region. When thepartition wall section is bonded to the reinforcing member, the movementof the partition wall section is restricted by the reinforcing member.Thus, vibration of the partition wall section can be prevented. As aresult, crosstalk between the ultrasonic transducer elements can beprevented. Further, when the movement of the partition wall section isrestricted, it is possible to avoid having the vibration of thepartition wall section act on the ultrasonic vibration of the ultrasonictransducer elements. Then, ultrasonic vibration in a clear vibrationmode can be obtained in the ultrasonic transducer elements.Consequently, when vibration of the partition wall section is avoided inthis way, it is possible to inhibit a decrease in the amplitude ofultrasonic vibration.

The reinforcing member may include a first surface overlaid on thesecond surface of the substrate, and the ventilation passage includes aplurality of groove parts formed on the first surface of the reinforcingmember. In this way, it is possible to ensure a ventilation passagerelatively easily.

The ventilation passage may include a plurality of groove parts formedon the second surface of the substrate. In this way, it is possible toensure a ventilation passage relatively easily.

At least a portion of one of the substrate and the reinforcing membermay be made of a porous material, and the ventilation passage mayinclude a plurality of pores of the porous material. In this way, it ispossible to ensure a ventilation passage relatively easily.

The ultrasonic transducer element chip may be incorporated in a probe.The probe may be provided with the ultrasonic transducer element chip,and a case member supporting the ultrasonic transducer element chip.

The probe may be incorporated in an electronic instrument. Theelectronic instrument may be provided with a probe, and a processingcircuit connected to the probe and configured to process output signalsof the ultrasonic transducer elements.

Similarly, the probe may be incorporated in an ultrasonic diagnosticdevice. The ultrasonic diagnostic device may be provided with a probe, aprocessing circuit connected to the probe and configured to processoutput signals of the ultrasonic transducer elements to generate animage, and a display device configured to display the image.

The ultrasonic transducer element chip may be incorporated in a probehead. The probe head may be provided with an ultrasonic transducerelement chip, and a case member supporting the ultrasonic transducerelement chip, and configured to be coupled to a probe main body of aprobe.

GENERAL INTERPRETATION OF TERMS

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts. Finally, terms of degree such as“substantially”, “about” and “approximately” as used herein mean areasonable amount of deviation of the modified term such that the endresult is not significantly changed. For example, these terms can beconstrued as including a deviation of at least ±5% of the modified termif this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. An ultrasonic transducer element chip comprising:a substrate defining an opening; an ultrasonic transducer elementdisposed at a position corresponding to the opening in a thicknessdirection of the substrate; and a reinforcing member connected to thesubstrate to cover the opening, the reinforcing member defining aventilation passage from the opening to an outside of the substrate.